Mechanical improvements to a personal vehicle

ABSTRACT

Improvements to personal vehicles including self-propelled and balancing personal vehicles. Ready detachability of a seat, footrest, seat back, control unit, wheels and caster assembly is provided using quick disconnect mechanisms.

TECHNICAL FIELD

The present invention pertains to mechanical improvements to personalvehicles including self-propelled personal vehicles.

BACKGROUND OF THE INVENTION

Personal vehicles, such as may be used by handicapped persons, may beself-propelled and user-guidable, and, further, may entail stabilizationin one or more of the fore-aft or lateral planes, such as when no morethan two wheels are in ground contact at a time. More particularly, suchvehicles may include one or more clusters of wheels, with wheels in eachcluster capable of being motor-driven independently of the cluster inits entirety. One example of such a vehicle is described in U.S. Pat.No. 5,701,965, which is incorporated herein by reference. Since personalvehicles operate under stringent constraints of weight and power, thefeatures of such vehicles are typically limited to those essential tothe propulsion of the vehicle, with safety left largely in the hands ofthe operator, and comfort largely foregone. Vehicles of this sort may bemore efficiently and safely operated employing mechanical featuressupplementary to those described in the prior art.

SUMMARY OF THE INVENTION

In accordance with a preferred embodiment of the invention, there isprovided a personal vehicle for carrying a payload including a user. Thevehicle has a ground-contacting module that supports the payload and hasat least one ground-contacting member. The vehicle also has a motorizeddrive arrangement, mounted to the ground-contacting module, that causesautomatically balanced operation of the vehicle in an operating positionthat is unstable with respect to tipping when the motorized drivearrangement is not powered. The vehicle has a seat for supporting theuser, the seat being coupled to the ground-contacting module in such amanner that the seat may be removed without the use of a tool, such asby means of a quick-disconnect assembly.

In accordance with another embodiment of the present invention, thepersonal vehicle has a footrest coupled to the ground-contacting modulefor supporting the foot of the user, where the footrest may also bedecoupled from the ground-contacting module without the use of a tool.The footrest may be coupled to the ground-contacting module through theseat assembly such as by means of a mounting pin inserted in a J slot.

In accordance with another embodiment of the invention, there isprovided a personal transportation vehicle having a seat back coupled tothe seat assembly, the seat back being tiltable with respect to the seatassembly. The vehicle may also have a sensor arrangement that provides asignal corresponding to the tilt of the seat back. The seat back may bepositionable at one of a plurality of positions provided with respect tothe seat assembly, thereby positioning the CG of the user at a desiredposition with respect to the ground-contacting module.

In accordance with further embodiments of the invention, the personalvehicle may have at least one caster capable of being brought intoengagement with the ground during operation of the vehicle. In oneembodiment of the invention, motion of the caster in a direction havinga vertical component is coordinated with motion of the seat assembly ofthe vehicle. The caster assembly may be decoupled from theground-contacting module without the use of a tool, and may include asuspension mechanism for dampening transmission of vibration to thevehicle.

In accordance with another embodiment of the invention, the personalvehicle may have a power module disposed substantially beneath the seatassembly and contained substantially within the areal projection in thehorizontal plane of the seat assembly. The personal vehicle may have auser interface module for permitting a user to command the motorizeddrive arrangement and a differentially frangible coupling for attachingthe user interface module to the support structure.

In accordance with yet another embodiment of the invention, the personalvehicle may have a belt tensioning mechanism for tensioning a belt thattransmits torque from a motor to a rotary member having an axis ofrotation. The belt tensioning mechanism has a motor having a roller forengaging the belt and a cam plate. The cam plate has a slot ridge forreceiving the motor, a rotation ridge disposed eccentrically withrespect to the slot ridge, and a plurality of circumferential sprocketteeth. Finally, the tensioning mechanism has a transmission plate fixedwith respect to the axis of rotation of the rotary member, the motorhaving a rotational orientation defined with respect to the transmissionplate, the transmission plate having a substantially elliptical camplate rotation shelf for receiving the cam plate rotation ridge suchthat a lateral position of the motor with respect to the transmissionplate may be changed by rotation of the cam plate while the rotationalorientation of the motor remains substantially constant.

The personal vehicle may have a self-pulling mechanism for a wheelhaving a tapered bore and a hub. The self-pulling mechanism has an axlehaving a taper corresponding the bore of the wheel and a threaded end, aretaining ring seated on an inside groove of the hub of the wheel, and awheel nut having a threaded bore corresponding to the threaded end ofthe axle such that upon tightening the wheel is retained on the axle andupon loosening a force is applied to the retaining ring for removing thewheel from the axle.

In accordance with alternate embodiments of the invention, there isprovided a vehicle for carrying a payload having a power module withleft and right compartments capable of interchangeably receiving a powerpack, where the respective compartments of the power module may becoupled to redundant power circuits. The personal vehicle of embodimentsof the present invention may also have a handle having an adjustableextension for retention by an assistant in operating the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood by reference to thefollowing description, taken with the accompanying drawings, in which:

FIG. 1A is a side view of a personal vehicle employing embodiments ofthe present invention;

FIG. 1B is a rear view of the power base of the personal vehicle of FIG.1A;

FIG. 1C shows the same view as FIG. 1B, with the battery tray removed toshow the position of the electronics box;

FIG. 2 shows a front cross-sectional view of a swing-arm caster wheelsuspension assembly in accordance with an embodiment of the presentinvention;

FIG. 3 is an exploded view of the caster wheel suspension assembly ofFIG. 2;

FIG. 4 shows a front view in cross section of a mechanism for couplingthe caster suspension assembly of FIGS. 2 and 3 to a member of apersonal vehicle in accordance with an embodiment of the presentinvention;

FIGS. 5A-5B show side and top cross-sectional views of a seat supportingassembly for a personal vehicle showing a quick-disconnect coupling andlatch assembly in accordance with an embodiment of the presentinvention;

FIGS. 6A-6D show views of a transmission plate with drive motor mountingcam plate in accordance with an embodiment of the present invention;

FIG. 7A shows a side view in cross-section of a retaining structure fora user command interface coupling for a personal vehicle showing adifferentially frangible coupling between the user command interface andthe support of the personal vehicle in accordance with an embodiment ofthe present invention;

FIGS. 7B and 7C show embodiments of a latching tongue for thedifferentially frangible coupling mechanism of FIG. 7A;

FIG. 7D is a perspective view of a user command interface for a personalvehicle showing a latching tongue for the differentially frangiblecoupling of FIG. 7A;

FIG. 7E is an exploded view of the assembly of the differentiallyfrangible quick disconnect mechanism of FIG. 7A to the armrest of apersonal vehicle in accordance with an embodiment of the invention;

FIGS. 8A and 8B show side views of a wheel assembly including aself-pulling wheel mechanism in accordance with an embodiment of thepresent invention;

FIG. 8C shows a cross-sectional side view of the self-pulling wheelmechanism of FIG. 8A;

FIGS. 9A and 9B show a battery retention assembly, including rails forrapid battery switchout, for use in a personal vehicle in accordancewith an embodiment of the present invention;

FIGS. 10A-10C show views of a removable footrest assembly for awheelchair-type vehicle in accordance with an embodiment of the presentinvention; and

FIGS. 11A and 11B show components of an extensible attendant handle andseat back orientation sensor mechanism for a wheelchair-type vehicle inaccordance with an embodiment of the present invention;

FIG. 11C shows a front view of a magnetic sensor disk component of anorientation sensor mechanism in accordance with an embodiment of thepresent invention;

FIGS. 12A and 12B show diagrams illustrating mechanisms for adjustingthe seat depth of the seat back of a personal vehicle, in accordancewith embodiments of the present invention;

FIGS. 13A and 13B show perspective views of an embodiment of a seatassembly for use with a personal vehicle in accordance with anembodiment of the present invention;

FIGS. 13C and 13D show exploded and assembled views, respectively, of arotatable armrest support for use with a personal vehicle in accordancewith an embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1A, a side view is shown of a personal vehicle,designated generally by numeral 10. Vehicle 10 may be described in termsof two fundamental structural components: a support 12 for carrying apassenger 14 or other load, and a ground-contacting module 16 whichprovides for transportation of support 12 across the ground, or,equivalently, across any other surface. The passenger or other load maybe referred to herein and in any appended claims as a “payload” As usedin this description and in any appended claims, the term “ground” willbe understood to encompass any surface upon which the vehicle issupported.

A mechanism and process for automatically balanced operation of thevehicle in an operating position that is unstable with respect totipping when the motorized drive arrangement is not powered is describedin Kamen '965 column 3, line 55 through column 5, line 44.

Referring further to FIG. 1A, the modes of operation described hereinapply to vehicles having one or more ground-contacting elements 18,where each ground-contacting element is movable about an axis 20 andwhere the axis corresponding to a ground-contacting member can itself bemoved. For example, ground-contacting element 18 may be a wheel, asshown, in which case axis 20 corresponds to an axle about which thewheel rotates. Active control of the position of the axis 20 about whichground-contacting element 18 rotates may be tantamount to activesuspension of the vehicle in that the position may be controlled inresponse to specified conditions of the traversed surface or specifiedmodes of operation of the vehicle.

Motion of axes 20 of respective ground-contacting elements is referredto in this description and in any appended claims as “cluster motion”Wheels 18 may be movable in sets, with the moving assembly referred toas a cluster 36. Cluster motion is defined with respect to a second axis22, otherwise referred to as a “cluster joint” Additional driven degreesof freedom may be provided, such as motion of the second axis about oneor more pivots which may, in turn, allow the height of seat 28 to bevaried with respect to the ground. Alternatively, seat height may bevaried by means of a telescoping post, or by means of any othermechanical artifice. An actuator may be associated with each drivendegree of freedom and controlled using control strategies discussed indetail below. In preferred embodiments of the invention, the actuatorsinclude wheel servo-motors and cluster servo-motors, with currentsupplied to the respective motors by servo amplifiers. Additionally,non-driven wheels may be provided, such as casters or Ad pilot wheels 30coupled to footrest 32 or otherwise to support 12.

An advantage to providing one or more caster wheels 30 coupled tofootrest 32 is that such caster wheels may be engaged or disengaged withthe ground 34 by controlling the height of seat (or support) 12 withrespect to ground-contacting elements 18. The engagement of caster wheel30 for traversing curbs or other ground obstacles may comprise part of acontrol mode of the vehicle, as taught in copending U.S. provisionalpatent application, serial no. 60/124,403, filed Mar. 16, 1999, which isincorporated herein by reference. It is to be understood that one ormore caster wheels 30 may also be provided aft of support 12, and may becoupled to the support or, alternatively, may be controlled so as to begoverned by the height of support 12 with respect to ground-contactingelements 18. It is not required, within the scope of the invention, thata particular caster be in contact with the ground during all, or indeedany, of the duration of operation of the vehicle.

Referring to FIG. 1B, seat 12 is coupled to power base 8 of the personalvehicle at seat connection flange 256. Seat height is adjusted by seatheight mechanism 6. In order to allow traversal by personal vehicle 10of terrain of varied surface structure or varied topologies such asstairs, personal vehicle 10, it is advantageous to maximize clearanceboth beneath the vehicle and aft of the vehicle, the latter to permitmaximal maneuverability on descending stairs. Under circumstances wherea vehicle is not actively stabilized, it might be advantageous tooptimize the distribution of components in order simply to lower thecenter of gravity in the interest of stability. In an activelystabilized vehicle, and in accordance with preferred embodiments of theinvention, electronics module 4 and power pack shelf 462 areadvantageously disposed above cluster axis 22. Additionally, the rearcontour of ground-contacting module is cut away in a convex contour inregion 2, to provide clearance for the vehicle upon descent of stairs.Electronics compartment 4 contains controller tray 3, as shown in FIG.1C.

Under circumstances where one or more caster wheels 30 engage the groundduring operation of the personal vehicle 10, it is advantageous toreduce the transmission of vibration to the payload of the vehicle, forthe safety and comfort of the passenger. Referring now to FIGS. 2 and 3,wherein identical numerals identify the same or similar features of theinvention, a preferred embodiment of the invention is shown thatprovides an intermediate structure to dampen vibration and shock loadsthat would otherwise be transmitted from a caster to the vehicle andpayload. FIG. 2 shows a cross-sectional view is shown of suspension 200,looking toward the vehicle from the front. Caster 30, coupled to distalend 204 of caster arm 206, engages the ground under circumstancesdiscussed above. Caster arm 206 is pivotable about pivot 208 which maybe a pin 206 as shown in FIG. 3. Proximal end 210 of caster arm 208 isengaged within caster housing 212. Compression spring 214 is axiallyretained in compression about bolt is 216 between caster housing 212 andpreloading plate 220. Compression spring 214 pushes upward on proximalend 210 of caster arm 206, urging the caster arm against washer 218 andcaster housing 212.

Thus, in accordance with an embodiment of the invention shown in FIGS. 2and 3, suspension 200 may be preloaded by virtue of compression spring214 applying an upward force on the proximal end 210 of caster arm 206.The upward force on proximal end 210 acts about pivot 208 to keep casterwheel 30 in contact with the ground. Caster wheel 30 may advantageouslyrespond to bumps and dips in the ground surface because spring 214 takesup, as potential energy, that kinetic energy that would otherwise betransmitted to the payload. FIG. 3 shows an exploded view of thecomponents of the swing-arm caster wheel suspension assembly of FIG. 2.Caster arms 206 are shown pivotable about pivot pins 208 which traversecaster housing 212. Springs 214 are also shown as are washer 218, bolts216, and preloading plate 220.

Another feature of caster suspension 200 is now described with referenceto FIG. 3 and with additional reference to FIG. 4. In accordance with apreferred embodiment of the invention, caster suspension is coupled to acaster mount 222 (shown in FIG. 10A) through which caster suspension 200is, in turn, coupled to support 12 (shown in FIG. 1), i.e., to the seatassembly. For purposes of storage or for ready transportation of thepersonal vehicle in an automobile, for example, it is advantageous thatthe vehicle be readily collapsible, and, in particular, it isadvantageous that caster suspension 200 be readily detachable from itscoupling to the support assembly. Caster housing 212 is clamped tocaster mount 222 by means of a pair of quick-disconnect clamps 224 and226. Quick-disconnect clamps 224 and 226 each contain wedged slots 228that apply lateral force to mating flanges of caster housing 212 andcaster mount 222, thereby retaining them with a small clamping forceapplied by cams 230 as latch levers 232 are rotated to urgequick-disconnect clamps 224 and 226 about caster housing 212 and castermount 222. A cross-sectional view of flange 240 of the seat assembly andflange 242 of the caster suspension as clamped by quick-connect wedgeclamp 224 is shown in FIG. 4. Wedge clamps 224 and 226 and latch levers232 are pivotably coupled to caster housing 212 and are retained withthe caster suspension assembly 200 upon disassembly from the vehicle.

Referring now to FIG. 5A, a side view is shown in cross-section of aquick seat disconnect assembly 250 for a personal vehicle 10. Seat stem252 terminates at flange 254 which is tapered in conjunction with acorresponding taper on flange 256 of vehicle base 258 in such a mannerthat Marmon or jaw clamps 260 may be applied to couple flanges 254 and256. Seat stem 252 is thus readily disconnected from vehicle base 258without requiring the use of a tool. Springs 262 are mounted betweenflanges 254 and 256 so as to urge clamps 260 outward. Referring now toFIG. SB, a pair of bolts 264 connect clamps 260 and 266 and prevent theclamps from falling off flanges 254 and 256. Bolts 264 are attached tohandle housing 268. Handle housing 268 contains a handle 270, pivotallymounted about pivot 272 with respect to handle housing 268. Handle 270is shaped such that in one position end 274 of handle 270 applies aforce against clamp 266 adjacent to handle housing 268. When handle 270is rotated, the force on clamp 266 is removed and clamps 260 and 266 canbe removed and seat stem 252 disconnected from vehicle base 258.

Referring now to FIGS. 6A-6D, views are shown of a transmission belttensioning mechanism 300 advantageously employed in the wheel drive ofpersonal vehicle 10 in accordance with a preferred embodiment of theinvention. Referring first to the outside view of FIG. 6A, belttensioning mechanism 300 may advantageously conserve the angularorientation of wheel motor 302 so that power and control cables (notshown) need not be disturbed as the position of wheel motor 302 istranslated with respect to wheel transmission plate 304 in order totension a belt or chain or other endless loop driven by the shaft ofwheel motor 302. The view of FIG. 6A is referred to herein as an‘anterior’ view of the transmission plate. FIG. 6B shows the posteriorside of transmission plate 304 and, more particularly, shows shaft 306of wheel motor 302 extending through wheel transmission plate 304. Beltroller 307 is rigidly coupled to motor shaft 307 for transmission oftorque to a belt (not shown). Similarly, a sprocket may also be providedfor driving a chain in an analogous manner. From this view, it is clearthat motor shaft 306 extends through eccentric shaft opening slot 308,the function of which will now be described.

FIG. 6C shows an exploded anterior view of transmission plate 304 fromwhich the wheel motor has been removed to clearly show shaft openingslot 308. Motor 302 is seated within slot ridge 310 of tensioning camplate 312. The sprockets 314 of cam plate 312 are disposed eccentricallywith respect to the slot ridge and the rotation ridge 316, shown in FIG.6D. Rotation ridge 316 is seated, in turn, in cam plate rotation shelf318 such that rotation of cam plate 312, in the manner of a Scotch yoke,results in lateral translation of the shaft of the motor while theorientation of the motor with respect to the transmission plate may bekept constant. Once the motor has been translated to the point where aspecified belt tension is attained, bolts are tightened to secure themotor housing to the transmission plate through the sprockets of the camplate, thereby securing the motor against both rotation and translation.

Referring now to FIGS. 7A-7C, a side view is shown in cross-section of afrangible coupling, advantageously employed for retaining a user commandinterface (not shown) in conjunction with a personal vehicle 10 so thatthe user command interface may either be attached to an armrest of thevehicle, for example, or detached for remote operation via a cable, suchas retractable cable, or via wireless communication with the personalvehicle. In a preferred embodiment of the invention, a user commandinterface 376 (shown in FIG. 7D) is readily disconnected from armrest378 (shown in FIG. 7D) of support 12 (shown in FIG. 1) by means of anasymmetrical quick disconnect mechanism 350, shown in a cross-sectionalside view in FIG. 7A. FIG. 7B shows a side view in cross-section of anasymmetrical latching tongue for retention by quick disconnect mechanism350. When latching tongue 352 is engaged in quick disconnect mechanism350, an upper roller 354 engages upper notch 356 while a lower roller358 engages lower notch 360. Upper roller 354 is urged downward bycompression spring 362 acting against rocker arm 364 which pivots aboutpivot 366. Since lower face 368 of latching tongue 352 is beveled, thelatching tongue, and the user command interface to which it is attached,are relatively easily removed from the quick-disconnect mechanism 350 bypulling the user command interface in an upward direction. By way ofcontrast, upper face 370 of the latching tongue 352 runs horizontallysubstantially to the tip 372 of tongue 352. Thus, the user commandinterface may not be as readily removed from the quick-disconnectmechanism 350 by pressing the user command interface in an downwarddirection. Typically, a force in excess of 25 pounds is required toremove latching tongue 352 by pushing downward on it with respect toquick disconnect mechanism 350, whereas detachment can be achieved bypulling up on latching tongue with a force not exceeding 2 pounds. Thisdifferential frangibility is advantageous in preventing accidentaldetachment and breakage of the user command interface. Since notches 356and 360 are substantially parallel grooves over the width of thelatching tongue 352, there is substantially no free play in the capturedtongue, and side breakaway forces are substantially greater than eitherupward or downward breakaway forces. Of course, within the scope of theinvention, the grooves may be oriented otherwise so as to providedifferential frangibility favoring extraction of the tongue toward anyspecified direction, as will be readily evident to a person skilled inthe art. FIG. 7C shows a cross-sectional view from the side of latchingtongue 352, wherein, in accordance with an alternate embodiment of thepresent invention, an auxiliary groove 374 is provided between uppergroove 356 and tip 372. If the user command interface is accidentallydetached by force applied in a downward direction and upper roller 354no longer engages upper groove 356, upper roller 354 will still engageauxiliary groove 372 and the unit will not detach freely, as a safetyfeature and to prevent breakage.

Referring now to FIG. 7D, a perspective view is shown of a user commandinterface 376 for a personal vehicle showing latching tongue 352 of thedifferentially frangible coupling mechanism that has been described. Anexploded view is shown in FIG. 7E of the assembly of the differentiallyfrangible quick disconnect mechanism 350 of FIG. 7A to armrest 378 of apersonal vehicle by means of fasteners such as screws 380. In accordancewith an embodiment of the invention, one of a series of icons may bedisplayed to the user on visual display monitor 377 (shown in FIG. 7D),with each distinct icon characterizing a corresponding mode of operationof the personal vehicle.

Referring now to FIGS. 8A-8C, a self-pulling wheel assembly 400 is shownfor removal of a wheel 402. FIGS. 8A and 8B show side views of thecomponents of the assembly, while FIG. 8C shows a cross-sectional view.Axle bore 404 of wheel 402 has a tapered inside surface 406corresponding to the taper of axle 408 so that torque may be transferredfrom axle 408 to the wheel. Wheel 402 is mounted by pressing axle bore404 onto axle 408 by driving wheel nut 410 onto threaded spindle 412 ofaxle 408. Wheel nut retention clip 420 retains the wheel nut againstrotation with respect to the wheel hub. Hub 414 of wheel 402 has aretaining snap ring 416 that is snapped into an annular groove 418behind wheel nut 410. Thus, wheel nut 410 is captured between the wheeland the retaining ring. Retaining ring 416, in a preferred embodiment,is a snap ring. By unscrewing nut 410 in an outward direction, anoutward force is exerted on hub 414 through ring 416, thereby pullingthe wheel 402 off axle 408. Thus the wheel may advantageously be pulledwithout application of a separate puller tool.

Referring now to FIG. 9A, a perspective view is shown of a battery pack,designated generally by numeral 450, that may be used to supplyelectrical power to a personal vehicle. Any source of electrical powerinternal to battery pack, such as chemical cells of any sort known inthe art, is within the scope of the present invention. Battery pack 450is configured, as will be described, for convenient insertion andextraction of the battery pack to provide for ready switchout when itbecomes necessary to renew or recharge the energy source, or fordisassembly and shipping of the personal vehicle. In accordance with apreferred embodiment of the invention, up to two power packs 450 areborne by the power base 6 (shown in FIG. 1) of personal vehicle 10beneath seat pan 28 and proximate to the seat. Electrical power issupplied by battery pack 450 to power base 6 via electrical connector452 that engages a mating connector (not shown) when battery pack 450 isfully inserted into a battery tray in the power base. Battery pack 450is guided into position in the battery tray by guides 460 extendingabove shelf 462 of the battery tray, as shown in FIG. 9B. Guides 460ride within battery tray slots 454 as the battery pack is removed orinserted, thus ensuring straight insertion and proper coupling ofconnector 452 with its counterpart in the power base. After insertion ofone of the battery packs 450, retaining latch 464 (shown in FIG. 9B) isclosed behind the inserted battery pack, urging the pack into its fullyinserted position and into electrical contact with the power base. Whenretaining lever 464 is opened, battery pack 450 is urged out of itsinserted position, and out of electrical contact with the power base, byoperation of a compressed spring (not shown) against spring ledge 456.Thus, power is not delivered by the battery pack unless it isaffirmatively retained by the battery retaining latch 464. Battery pack450 and the battery tray of the power base have complementarysymmetries, such that battery pack 450 may be inserted into either theleft-hand or right-hand battery slot by rotating the battery pack aboutits long axis. In a preferred embodiment, each battery pack powers aseparate power base control circuit, thus providing full redundancy.Additionally, the interchangeability of the battery packs 450 mayadvantageously prolong the lifetime of the battery packs if the powerdrain on the respective sides of the battery tray is uneven.

FIG. 9B shows shelf 462 of the battery tray with the right batteryretaining latch 464 shown in a closed position, and the left batteryretaining latch 466 shown in an open position. Lever locking sleeve 468slides over both left and right retaining latches, thus locking bothbattery packs in place for safety of operation.

FIG. 10A is a perspective view of a footrest assembly, designatedgenerally by numeral 700, attached to seat pan assembly 702. The rearportion of the seat pan assembly has been cut away for easier viewing. Afootrest 704 is attached to a pair of lower footrest legs (not shown)which telescope inside the upper footrest legs 706 thereby providing afootrest length adjustment. The lower legs are locked in place by a pairof extension locks 708. A tilt adjustment assembly 710 spans the twoupper footrest legs 706 and can slide along the upper footrest legs.Tilt assembly 710 includes a front piece 712 and a rear 714 piece thatare attached to each other by screws 716. The ends of the front and rearpieces capture the upper legs. When screws 716 are loosened, tiltassembly 710 can slide along the upper legs 706 but when screws 716 aretightened, the tilt assembly 710 is locked into place. Rear tiltassembly piece 714 extends perpendicular to the plane defined by the twoupper legs and rests against the caster mount face 698 of caster mount222. Moving the tilt assembly 710 upward on the upper legs 706 increasesthe tilt angle 718 of the footrest assembly 700. The terminal end 720 ofeach of the upper legs 706 is cut away to engage the footrest assembly700 onto the seat pan assembly 702. The terminal end of each of theupper legs has a footrest mounting pin 722 that engages the footrestassembly mount 724 and forms a pivot for the tilt assembly.

FIG. 10B is a side view of the seat pan assembly 702. Footrest assemblymount 724 has a truncated elliptical profile with a J slot 726 toaccommodate the footrest mounting pin 722 (shown in FIG. 10A). FIG. 10Cshows a detailed side view of the terminal ends 720 of the footrestassembly engaging the footrest assembly mount 724. Terminal ends 720 ofthe footrest assembly are initially positioned perpendicular to thecaster mount face 698 and are slid into the footrest assembly mount 724until the mounting pin 722 slides into the J slot 726 of the assemblymount. The truncated elliptical profile is preferred so that theterminal ends of the footrest assembly can slide over the truncatedportion of the assembly mount. The terminal ends have a front cut-awayand a rear cut-away. The depth of the front cut-away is dimensioned suchthat when the mounting pin is at the end of the J slot, the terminal endcan be rotated into the downward configuration without interferencebetween the front cut-away and the curved portion of the assembly mountwhile at the same time preventing upward motion of the footrest assemblyrelative to the assembly mount. The rear cut-away depth is dimensionedto allow the terminal ends to slide over the assembly mount duringmounting or dismounting of the footrest assembly from the seat panassembly. In accordance with the embodiments described, the footrestassembly may advantageously be disassembled from the personal vehiclewithout operation of any screws or other fasteners and without the useof tools.

FIG. 11A shows a seat back assembly 730 for a personal vehicle, with theseat back cover removed. In accordance with a preferred embodiment ofthe invention, a handle 732 is provided to permit an assistant to exertforces on the vehicle. Operation of a balancing personal vehicle in anassisted mode of operation is described in copending provisionalapplication 60/124,403. The height of handle 732 may be adjusted,typically over a range of 18-20 inches above seat back 734, using anymethod of locking telescoping members known in the mechanical arts,such, for example, as wedge clamps secured by tightening of handleadjustment locks 736.

Referring to FIG. 11B, seat back 734 may be tilted and locked in varioustilted positions by engaging locking pins 750, urged by locking pinsprings 752, into one of several locking pin holes 754 as seat back 734pivots about tilt pivot 748. Tilt plates 756 disposed on either theright or left sides of the seat pan, or both, allow adjustment of theseat back with respect to seat pan mount 760 to fit the user. Lockingpins 750 are activated by a cable 753 actuating a locking pin cam 758 orotherwise as known to persons skilled in the mechanical arts.

In order to provide information to controller 2 as to the currentposition of seat back 734, a sensor mechanism 762 is provided. Sensormechanism 762 includes a magnetized orientation plate 764 with respectto which the seat back moves as it is being tilted, and magnetic sensorsfixed with respect to the seat back. In a preferred embodiment, twomagnetic sensors, such as Hall effect sensors, for example, are mountedin sensor mounting holes 766 so as to sense the pattern of magnetizationof orientation plate 764 as it passes by the sensors. The magnetizationpattern of magnetized orientation plate 764, in accordance with apreferred embodiment, is shown in FIG. 11C, where the hatched areas aresouth magnetic pole and the unhatched areas are north pole. Theasymmetry of the magnetization pattern allows the resolution, withredundancy, of three positions using only two sensors. The use ofdiffering magnetization patterns and numbers of sensors are also withinthe scope of the invention.

The location of the center of gravity (CG) of the user is important on adynamically stabilized personal vehicle because it determines thedesired pitch angle which the power base tries to maintain whetheroperated in a balancing mode, on fewer than three wheels, or in anenhanced stability mode wherein the vehicle may otherwise be staticallystable. The CG plays a role in determining the stability even of avehicle operated in a mode that is not actively stabilized. Therefore,it is desirable to provide for controlling the location of the user's CGvia seat adjustments.

FIG. 12A shows a schematic diagram of one seat adjustment scheme, inaccordance with an embodiment of the invention, where back frame 800 ofseat 802 is fixed in location with respect to power base 804. Seat 802,which is attached to power base 804 via seat quick-disconnect 806discussed above in reference to FIG. 5, is positioned for the smallestlikely user 808 so that the user's legs 810 can clear the power base804, and then the seat pan 812 is lengthened to accommodate larger users814. Although mechanically simple, this seat adjustment scheme resultsin the CG 816 of the large user being far forward of the desiredposition, which is directly over the cluster axis 818, along a linedesignated 820. The problem is further exacerbated by the fact that thelargest user is also the heaviest, making the gravitational torqueplaced on the system by the user (about the point of contact 822 of theforward wheel, for example) or dramatically larger.

FIG. 12B shows a further seat adjustment scheme, in accordance with apreferred embodiment of the invention, where the front edge 824 of theseat pan 812 is fixed with respect to the power base 804, and the seatsize is adjusted by moving the seat back in the aft direction. Thisresults in the CG of the large user 814 and the CG of the small user 808remaining relatively close to the desired location. To further optimizethe seat adjustment, the entire seat location may be made adjustable inthe fore-aft direction, allowing optimal placement of the CG for allusers.

Referring now to FIG. 13A, a perspective view is shown of an embodimentof a seat assembly 850 for use with a personal vehicle. Caster assembly200 is shown, as described above with reference to FIGS. 2-4. Also shownare footrest assembly 700 (described with reference to FIGS. 5A-5B),seat pan 812, armrest 378, rotatable armrest support 848, extensibleattendant handle 732, and seat back 734. The seat pan assembly,designated generally by numeral 702, is shown in greater detail in theperspective view from below of FIG. 13B. Seat pan 812 is drilled witharmrest assembly mounting holes 852 for attachment of an armrestassembly as described below. The multiplicity of armrest assemblymounting holes, along with the provision for changing the size of theseat pan allow flexibility in tailoring the seating arrangement to thedimensions of the occupant of the seat. To provide additionalflexibility, and to optimize placement of the CG of the user asdiscussed above with reference to FIGS. 12A and 12B, multiple seat backassembly mounting holes 854 are provided in seat runner weldment 856.Flange 254 of seat stem 252 is shown as used in conjunction with theseat quick-disconnect mechanism described above in reference to FIGS. 5Aand 5B. FIG. 13C shows an exploded view of rotatable armrest support848, and FIG. 13D shows an assembled view of the same rotatable armrestsupport. The height of armrest 378 (shown in FIG. 13A) may be adjustedto suit the user, in accordance with an embodiment of the invention, byraising or lowering upper riser weldment 860 which slides inside armrestbracket weldment 862. Upper riser weldment 860 is locked into place bytightening torque collar screw 864 on shaft collar 866. Pivot weldment868 is notched to accept armrest tilt locking pin 870 on armrest bracketweldment 862 so as to lock the armrest riser in the upright position.The armrest may be rotated by pulling the armrest riser outward, therebycompressing spring 872 and disengaging pin 870 from notch 874. Slots 876allow for adjustment of the position of the armrests as weldment 868 issecured to the seat pan.

The described embodiments of the invention are intended to be merelyexemplary and numerous variations and modifications will be apparent tothose skilled in the art. All such variations and modifications areintended to be within the scope of the present invention as defined inthe appended claims.

We claim:
 1. A vehicle for carrying a payload including a user, thevehicle comprising: a) a ground-contacting module that supports thepayload, the ground-contacting module including at least oneground-contacting member; b) a motorized drive arrangement, mounted tothe ground-contacting module, the drive arrangement causing, whenpowered, automatically balanced operation of the vehicle in an operatingposition that is unstable with respect to tipping when the motorizeddrive arrangement is not powered; c) a seat assembly for supporting theuser, the seat assembly being rigidly coupled to the ground-contactingmodule at a single seat connection flange in such a manner that the seatassembly may be removed without the use of a tool; and d) at least onecaster coupled to the seat assembly, the vehicle being operable witheach caster either engaging or not engaging the ground, each castermoving with respect to the seat assembly only in response to groundengagement.
 2. A vehicle for carrying a payload including a user, thevehicle comprising: a) a ground-contacting module that supports thepayload, the ground-contacting module including at least oneground-contacting member; b) a motorized drive arrangement, mounted tothe ground-contacting module, the drive arrangement causing, whenpowered, automatically balanced operation of the vehicle in an operatingposition that is unstable with respect to tipping when the motorizeddrive arrangement is not powered; c) a seat assembly for supporting theuser, the seat assembly being rigidly coupled to the ground-contactingmodule at a single seat connection flange by a quick-disconnectmechanism; and d) at least one caster coupled to the seat assembly, thevehicle being operable with each caster either engaging or not engagingthe ground, each caster moving with respect to the seat assembly only inresponse to ground engagement.
 3. A personal vehicle for carrying a userhaving a center of gravity (CG), the vehicle comprising: a) aground-contacting module for conveying the user across a surface; b) aseat assembly coupled to the ground-contacting module for supporting theuser in a seated position; c) a seat back coupled to the seat assemblyat one of a plurality of positions, thereby positioning the CG of theuser at a desired position with respect to the ground-contacting module;and d) at least one caster coupled to the seat assembly, the vehiclebeing operable with each caster either engaging or not engaging theground, each caster moving with respect to the seat assembly only inresponse to ground engagement.
 4. A vehicle according to any of claims1, 2, or 3, wherein the at least one caster may be moved in a directionhaving a vertical component during operation of the vehicle.
 5. Avehicle according to any of claims 1, 2, or 3, wherein the at least onecaster is coupled to the seat assembly in such a manner that the atleast one caster can be decoupled from the seat assembly without the useof a tool.
 6. A vehicle according to any of claims 1, 2, or 3, whereinthe at least one caster is coupled to the seat assembly by means of aquick-disconnect mechanism.
 7. A vehicle in accordance with any ofclaims 1, 2, or 3, further including a caster suspension mechanism fordampening transmission of vibration to the vehicle.
 8. A vehicle inaccordance with claim 7, wherein the suspension mechanism is a swing-armsuspension.
 9. A vehicle for carrying a payload including a user, thevehicle comprising: a) a seat assembly for supporting the user in aseated position, the seat assembly having a footprint in a horizontalplane; b) a ground-contacting module coupled to the seat assembly; c) amotorized drive arrangement coupled to the ground-contacting module forpowered operation of the vehicle; and d) a power module supplying energyto the motorized drive arrangement, the power module disposedsubstantially beneath the seat assembly.
 10. A vehicle in accordancewith claim 9, wherein the power module is contained substantially withinthe footprint of the seat assembly.
 11. A vehicle for carrying a payloadincluding a user, the vehicle comprising: a. a ground-contacting modulethat supports the payload, the ground-contacting module having arotating member characterized by an axis of rotation; b. a motorizeddrive arrangement including a motor, the motorized drive arrangementbeing coupled to the ground-contacting module for powered operation ofthe vehicle; c. a belt that transmits torque from the motor to therotating member; d. a cam plate having a slot ridge for receiving themotor, a rotation ridge disposed eccentrically with respect to the slotridge, and a plurality of circumferential sprocket teeth; and e. atransmission plate fixed with respect to the axis of rotation of therotating member, the motor having a rotational orientation defined withrespect to the transmission plate, the transmission plate having asubstantially elliptical cam plate rotation shelf for receiving the camplate rotation ridge such that a lateral position of the motor withrespect to the transmission plate may be changed by rotation of the camplate while the rotational orientation of the motor remainssubstantially constant.
 12. A personal vehicle comprising: a. aground-contacting module for bearing the vehicle across a surface; b. asupport structure coupled to the ground-contacting module for supportinga payload; c. a motorized drive arrangement for propelling theground-contacting module with respect to the surface; d. a userinterface module for permitting a user to command the motorized drivearrangement; and e. a coupling for attaching the user interface moduleto the support structure, the coupling having breakaway loadsspecifiable as a function of orientation of the breakaway with respectto the support structure.
 13. A personal vehicle in accordance withclaim 12, wherein the breakaway load in a downward direction exceeds thebreakaway load in an upward direction.